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Electrospinning of Modified Biopolymers for Medical Applications
Pavliňáková, Veronika ; Martinová,, Lenka (oponent) ; Zajíčková, Lenka (oponent) ; Vojtová, Lucy (vedoucí práce)
Proposed dissertation thesis is dedicated to the preparation and characterization of novel biocompatible nanofibers with both biological and medical potential applications. The main emphasis of this thesis was focused on the preparation of composite nanofibers respecting the principles of "green chemistry", meaning hard requirements of tissue engineering. The theoretical part summarizes knowledge about the electrospinning process and its parameters. The literature review also describes the electrospinning of proteins like collagen and gelatin, their blends with synthetic polymers and biopolymers as well as with inorganic fillers. One chapter deals with various kinds of crosslinking agents to improve nanofiber hydrolytic stability. The last chapter is aimed to halloysite inorganic nanotubes (HNT) gaining much attention for the use as drug carrier due to its remarkable physical (mechanical reinforcement) and biological (biocompatibility and low toxicity) properties. The experimental part is divided into two chapters, each of them examines issues of nanofibrous material preparation from different perspective. The first part is focused on novel hydrolytically stable antibacterial gelatin nanofibers modified with oxidized cellulose. The unique inhibitory effect of the nanofibers was examined by luminometric method using genetically modified Escherichia coli strain. Seeded adenocarcinoma lung cells proved good adhesion and proliferation. Second experimental part explores the effect of source and amount of natural tubular halloysite on the structure and properties of biocompatible amphiphilic nanofibers based on a polycaprolactone and gelatin. The addition of HNT improved the thermal stability, mechanical properties (both stiffness and elongation) and reduced the crystallinity of nanofibers. The HNT from different sources did not affect the cell behavior but slightly influenced the proliferation and viability of cells on nanofibers.
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Polykaprolakton, jeho syntéza, charakterizace a degradabilita
Boháčová, Zdeňka ; Vojtová, Lucy (oponent) ; Hermanová, Soňa (vedoucí práce)
Předložená diplomová práce se zabývá studiem polymerace za otevření kruhu (ROP) kaprolaktonu katalyzované pomocí nových organických a organokovových sloučenin. V teoretické části práce jsou na základě literární rešerše popsány přehledy syntetických strategií a katalytických/iniciačních systémů pro ROP laktonů. V experimentální části byla provedena série polymerací -kaprolaktonu zaměřená na studium polymeračních podmínek (poměry rozpouštědlo/monomer, katalyzátor/iniciátor, monomer/iniciátor a koncentrace monomeru) v rozmezí teplot 25-70 °C. Provedená experimentální studie byla zaměřena na katalytické prekurzory na bázi organických karbenů (tBuNCH=CHN+tBu)CH Cl- (NHC-tBu) v roztoku tetrahydrofuranu a triazolového komplexu hliníku {O,O’-[4,5-P(O)Ph2tz]-AlMe2}, Ph = fenyl, tz = triazol, (OAlMe2) v roztoku chlorbenzenu. Připravené polymery byly charakterizovány pomocí 1H NMR spektroskopie (Bruker Avance), diferenciální skenovací kalorimetrie (TA Instruments Q 2000) a gelové permeační chromatografie (Agilent Technologies 1100 series). U připraveného vzorku s Mn = 12 kg/mol, Mw/Mn = 2,5 a se stupněm krystalinity 53 % byla otestována degradabilita účinkem mikroorganismu. Polymer ve formě lisované fólie a prášku byl vystaven působení bakteriálního kmene Bacillus subtilis (BS) v minerálním a živném médiu po dobu 42 dnů. Rastrovací elektronová mikroskopie (SEM) a konfokální laserová rastrovací mikroskopie (CLSM) potvrdily vývoj trhlin na povrchu filmu v porovnání s nezměněným povrchem kontrolních vzorků jako následek mikrobiálního ataku. Dále bylo pozorováno rozvinutí růžového zbarvení suspenze polymeru v důsledku aktivity mikroorganismu.
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Crystallization of binary polylactide blends and their morphology
Debnáriková, Michaela ; Poláček, Petr (oponent) ; Bálková, Radka (vedoucí práce)
Master thesis deals with the influence of polyvinylacetate, polycaprolactone, poly(butylene-adipate-co-terephtalate) and talc, ethylenevinylacetate, polyethylene glycol and monosodium citrate on the flow properties, mechanical properties and crystallization ability of PLA. The flow properties were studied using the melt flow index and mechanical properties were studied using a tensile test. The crystallinity was studied by differential scanning calorimetry and on a polarization optical microscope equipped with hot stage. Isothermal crystallization was performed at 95 and 105 °C for 3 h and non-isothermal crystallization was performed with a calorimeter at two cooling rates (1 and 10 °C/min). Upon the isothermal crystallization at 95 °C, the formation of denser crystalline structure was observed and the content of crystalline phase increased in most of the samples. The formation of spherulitic structure was observed at 105 °C in samples with 30 % PVAc, 30 % EVA and PEG. Reducing the cooling rate to 1 °C/min at non-isothermal crystallization had nearly no effect on the crystallization process of the most samples; the content of crystalline phase increased in the samples containing PBAT and PEG, which revealed double melting peak during subsequent heating. The crystalline fraction was the most significantly affected by the addition of PEG. All added polymers except PVAc affected the mechanical properties; PBAT, PCL, EVA and PEG increased the strain and decreased the strength and modulus of elasticity. The samples containing monosodium citrate showed unsatisfactory mechanical properties and could not be measured. The samples containing higher concentration of EVA copolymer showed the phase separation.
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Comparison of various amination methods of polycaprolactone concerning their effectivity in tissue engineering
Kováč, Ján ; Lehocký, Marián (oponent) ; Zajíčková, Lenka (vedoucí práce)
This diploma thesis dealt with the comparison of different methods of amination of polycaprolcatone in terms of their effectiveness for tissue engineering. A polycaprolactone membrane was prepared by an electrospinning method, which was subsequently modified by three different amination methods. Selected types of amination were plasma polymerization with cyclopropylamine monomer, hybrid modification using plasma and N-allylmethylamine monomer, and chemical amination using aminolysis with diaminohexane. Surface amines were subsequently characterized by electron scanning microscopy (SEM), X-ray photoelectron spectroscopy (XPS), attenuated total reflection infrared spectroscopy (ATR-FTIR) and contact angle measurement. A cell culture designated A375 (Human malignant melanoma cell lines A375® CRL-1619®) was cultured on the thus modified membranes, which was analyzed by optical microscopy, and a proliferation assay was performed by determining the relative amount of ATP. Based on the experimental results, we can confirm the success for all types of amination. In terms of efficiency for tissue engineering, the amination method by plasma polymerization with the monomer cyclopropylamine has the most satisfactory results.
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Polymerace a kopolymerace e-kaprolaktonu pomocí organických a organokovových katalyzátorů
Smrčková, Markéta ; Vojtová, Lucy (oponent) ; Hermanová, Soňa (vedoucí práce)
Alifatické polyestery představují díky své biodegradabilitě a biokompatibilitě skupinu vhodných kandidátů pro oblast biomateriálů. Jejich praktické využití v biomedicíně je však podmíněno dostupností reprodukovatelné syntézy definovaných produktů s absencí reziduí katalyzátorů působících v lidském těle nežádoucí imunologickou odezvu. Teoretická část práce se zabývá přehledem iniciačních/katalytických systémů a syntetických strategiíí přípravy polykaprolaktonu. Cílem této práce bylo v připravených polyesterech experimentálně ověřit přítomnost stop katalyzátorů na bázi organických karbenů a organokovových komplexů hliníku. Série vzorků polykaprolaktonu (PCL) byla přečištěna pomocí reprecipitace v methanolu při -10 °C. Přítomnost katalytických reziduí v PCL po každém čistícím kroku byla sledována pomocí 1H NMR (Bruker Avance). Reziduální množství hliníku bylo stanoveno pomocí atomové absorpční spektrometrie (AAS) a hmotnostní spektrometrie s indukčně vázaným plazmatem (ICP MS).
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Surface treatment of biocompatible materials
Kováč, Ján ; Kučera, František (oponent) ; Krčma, František (vedoucí práce)
This bachelor thesis deals with the study of the influence of plasma discharge on changes in the surface properties of the biomaterial. Surface treatements were performed using three types of plasma discharge: gliding arc, dielectric barrier discharge (DBD) and microwave surface wave discharge. Various gaseous mixtures in plasma discharges and their effect on the surface treatment of the biomaterial were investigated. The selected biomaterial was aliphatic biopolymer polycaprolactone (PCL). It is a suitable surface treatment material, thanks to its biodegradability and easy processability. The PCL supplied by Sigma-Aldrich was in the form of pellets, witch had been converted to foil. The film samples were subsequentely exposed to plasma discharges. To characterize the surface properties of the polymer, surface energy was measured using a sissle drop method, a See System from Advex Instrumnets was used to measure. Based on experimental results, we can confirm that the surface has been modified. However, the plasma discharge modifications have led to hydrophilic and not hydrophobic properties of the biomaterial, with the best results in terms of hydrophilicity being achieved by microwave discharge with surface wave. Due to the negative results of the experiment, bactericidal effects were not investigated.
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Advanced preparation of inorganic (ceramic) particles and nanostructures
Šťastná, Eva ; Martinovou,, Lenku (oponent) ; Vojtová, Lucy (oponent) ; Částková, Klára (vedoucí práce)
An electrospinning process was used for bioactive nanofibrous structures preparation. Neat polycaprolactone nanofibres and polycaprolactone nanofibres containing hydroxyapatite nanoparticles were successfully prepared via electrospinning and characterized using scanning electron microscopy. Mechanical properties of the nanofibres were analyzed using uniaxial tensile strength test. Results of the testing showed strong influence of the nanofibres direction alignment and nanoparticles presence on the mechanical properties of the prepared structures. The direction alignment contributed to higher elastic modulus and failure stress regardless the presence of the hydroxyapatite nanoparticles in the structure. However, the direction alignment considerably reduced failure strain of the structure. An interesting phenomenon occurred by the composite nanofibres – the influence of the hydroxyapatite particles was more distinct by the random fibres (they worsened failure strain and failure stress of the random composite fibres) but the hydroxyapatite particles did not have such strong effect on the parallelly aligned fibres. The samples were then modified by surface low-temperature plasma treatment to improve biological properties of the nanofibres. Change of the nanofibres surface characteristics was examined by contact angle measurement by sessile drop method and by XPS spectroscopy. The contact angle measurement showed that the plasma treatment considerably increased structures hydrophilicity – was unmeasurable. The XPS analysis explained the effect of the plasma treatment on microscopical scale – the plasma treatment had affected only polymer constituent of the treated structure, the hydroxyapatite nanoparticles remained intact. Selected prepared structures were biologically tested. Test in simulated body fluid proved high bioactivity of the polycaprolactone/hydroxyapatite composite nanofibres through precipitation of calcium phosphates phases on the composite structures. Following in-vitro tests using living cell cultures (ISO 10993-5 and WST-8 test) proved beneficial influence of the hydroxyapatite in the structure and of the surface plasma treatment when bioactivity of the plasma treated composite structures increased 1.5 times compared to the neat as-spun polycaprolactone fibres.
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Advanced preparation of inorganic (ceramic) particles and nanostructures
Šťastná, Eva ; Martinovou,, Lenku (oponent) ; Vojtová, Lucy (oponent) ; Částková, Klára (vedoucí práce)
An electrospinning process was used for bioactive nanofibrous structures preparation. Neat polycaprolactone nanofibres and polycaprolactone nanofibres containing hydroxyapatite nanoparticles were successfully prepared via electrospinning and characterized using scanning electron microscopy. Mechanical properties of the nanofibres were analyzed using uniaxial tensile strength test. Results of the testing showed strong influence of the nanofibres direction alignment and nanoparticles presence on the mechanical properties of the prepared structures. The direction alignment contributed to higher elastic modulus and failure stress regardless the presence of the hydroxyapatite nanoparticles in the structure. However, the direction alignment considerably reduced failure strain of the structure. An interesting phenomenon occurred by the composite nanofibres – the influence of the hydroxyapatite particles was more distinct by the random fibres (they worsened failure strain and failure stress of the random composite fibres) but the hydroxyapatite particles did not have such strong effect on the parallelly aligned fibres. The samples were then modified by surface low-temperature plasma treatment to improve biological properties of the nanofibres. Change of the nanofibres surface characteristics was examined by contact angle measurement by sessile drop method and by XPS spectroscopy. The contact angle measurement showed that the plasma treatment considerably increased structures hydrophilicity – was unmeasurable. The XPS analysis explained the effect of the plasma treatment on microscopical scale – the plasma treatment had affected only polymer constituent of the treated structure, the hydroxyapatite nanoparticles remained intact. Selected prepared structures were biologically tested. Test in simulated body fluid proved high bioactivity of the polycaprolactone/hydroxyapatite composite nanofibres through precipitation of calcium phosphates phases on the composite structures. Following in-vitro tests using living cell cultures (ISO 10993-5 and WST-8 test) proved beneficial influence of the hydroxyapatite in the structure and of the surface plasma treatment when bioactivity of the plasma treated composite structures increased 1.5 times compared to the neat as-spun polycaprolactone fibres.
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Use of Nanomaterials in Fortification of Anastomoses on the Gastrointestinal Tract
Rosendorf, Jáchym ; Liška, Václav (vedoucí práce) ; Herrmann, Inge K. (oponent) ; Wexner, Steven D. (oponent)
Úvod: Hlavním tématem dizertační práce je užití nanovlákenných biodegradabilních materiálů pro podporu hojení střevních anastomóz v kolorektální chirurgii. Alterovaný proces hojení střevní anastomózy může vést k několika typům lokálních komplikací. Anastomotický leak je přitom jednou z nejzávažnějších. Těžký anastomotický leak způsobuje rozvoj peritonitidy, sepse a je tedy život ohrožujícím stavem. V řadě případů je nutná reoperace a na ni navazující intenzivní péče, prodloužení hospitalizace a často následné snížení kvality života pacienta. Dalším zdrojem pooperačních komplikací je i extenzivní tvorba peritoneálních adhezí. Ty jsou častou příčinou abdominálního diskomfortu, poruch pasáže, a jsou tak nejčastější příčinou re-admisí po kolorektálních chirurgických výkonech. Nanovlákenné materiály prokázaly v řadě aplikací pozitivní vliv na proces hojení. Naším cílem bylo vyvinout optimální biodegradabilní nanovlákenný patch pro prevenci anastomotického leaku a extenzivní tvorby peritoneálních adhezí. Metodika: Provedli jsme tři na sebe navazující experimentální studie na prasečích modelech. V Experimentu A jsme vyvinuli polykaprolaktonový patch a patch z kopolymeru polykaprolaktonu a kyseliny polymléčné. Ty jsme aplikovali na anastomózu na tenkém střevě prasete domácího. Zvířata byla sledována po 3...
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